A. Field of the Invention
This invention relates to the field of cushions. More particularly, this invention relates to a cushion made of gelatinous elastomer, gelatinous visco-elastomer, or materials with similar characteristics which has hollow columns that compress to provide cushioning and which buckle to relieve pressure peaks.
B. The Background Art
In the prior art, there have been numerous attempts to provide a cushion which achieves comfort by eliminating peak pressure areas and by evenly distributing the cushioning force over a broad surface area. The relevant prior art of which the inventor is aware is categorized and summarized below.
1. Foam Cushions: Foam cushions typically include open cell polyurethane foam because of its low cost and light weight. The open cells are, in effect, air bubbles within the polyurethane which can be compressed and from which air can escape when a force, such as the weight of a cushioned object, is placed on the foam. Alternatively, foam cushions may use closed cell foam, in which the cells contain air or another gas, but the cells are closed so that the air or gas cannot escape even when a compressive force is applied to the foam. Closed cell cushions tend to resist deformation more than similarly constructed open cell cushions. In function, foam cushions behave much the same as a spring, permitting the cushioned object to sink into the foam and to be supported by rebound pressure; the more the cushioned object sinks into the foam, the higher the rebound pressure. When the cushioned object is removed, the foam has a tendency to return to its original shape, a characteristic referred to as "shape memory."
A significant problem with foam cushions is that protruding portions of the object being cushioned are placed under the highest pressure due to the foam's spring-like behavior, resulting in pressure on the cushioned object not being equalized. "Pressure peaks," as defined herein, means areas of a cushioned object which are subject to the greatest amounts of pressure when placed upon a cushioning surface. Closed cell foam cushions tend to create even worse pressure peaks than open cell foam cushions due to their inability to permit gas to escape from their cells when the cushion is called on to support an object.
Examples of cushions that include foam are included in the following documents: U.S. Pat. No. 4,713,854 issued in the name of Graebe on Dec. 22, 1987; U.S. Pat. No. 4,709,431 issued in the name of Shaktman on Dec. 1, 1987; U.S. Pat. No. 4,628,557 issued in the name of Murphy on Dec. 16, 1986; U.S. Pat. No. 4,467,053 issued in the name of Markle on Aug. 21, 1984; U.S. Pat. No. 3,518,786 issued in the name of Holtvoigt on Jul. 7, 1970; and U.S. Pat. No. 5,335,907 issued in the name of Spector on Aug. 9, 1994, each of which is hereby incorporated in its entirety for the material disclosed therein.
The following patents include both foam and a gel or fluid (see discussion of gels below): U.S. Pat. No. 4,952,539 issued in the name of Hanson on Aug. 29, 1990; U.S. Pat. No. 5,147,685 issued in the name of Hanson on Sep. 15, 1992; U.S. Pat. No. 5,058,291 issued in the name of Hanson on Oct. 22, 1991; U.S. Pat. No. 5,255,404 issued in the name of Dinsmoor, III et al. on Oct. 26, 1993; U.S. Pat. No. 5,201,780 issued in the name of Dinsmoor, III et al. on Apr. 13, 1993; U.S. Pat. No. 4,842,330 issued in the name of Jay on Jun. 27, 1989; and U.S. Pat. No. 4,726,624 issued in the name of Jay on Feb. 23, 1988, each of which is hereby incorporated in its entirety for the material disclosed therein.
2. Fluid Cushions: Some in the prior art have attempted to design a comfortable cushion using some type of a flowable fluid (such as liquid, air, gas, emulsion, lubricated objects or particles, etc.) within one or more fluid-tight bladders. When an object is placed on the fluid cushion, or when an object resting on the cushion is re-positioned, the fluid flows within the bladder and the bladder correspondingly deforms to conform to the shape of the object being cushioned. This results in a cushion which tends to equally distribute a cushioning pressure across the entire contact surface of the object being cushioned, and maximizes the percentage of the surface area of the object which is under pressure. Correspondingly, this also eliminates or reduces pressure peaks on the cushioned object.
Prior art fluid cushions have a number of problems, however. First, when the object being cushioned is shifted or repositioned on the fluid cushion, instability may result. Second, depending upon the type of fluid used, the cushion may have a high thermal mass and a high rate of thermal transfer, resulting in a cushion which is cold to the touch and which tends to draw heat out of the object being cushioned. This can result in discomfort when the object being cushioned is a human being. Third, fluid cushions are typically very costly to manufacture. Fourth, due to the necessity of maintaining a fluid-tight bladder, fluid cushions may be unreliable due to the possibility of bladder puncture. Fifth, if a fluid cushion is not of sufficient thickness, the object being cushioned may displace enough of the cushioning fluid to bottom out against a base on which the fluid bladder is resting, resulting in little or no cushioning effect. Sixth, fluid cushions have little shape memory, so they do not return to their original shape when the cushioned object is removed. Consequently, fluid cushions do not have an aesthetically pleasing appearance and are typically not considered appropriate for furniture. Seventh, fluid cushions typically do not permit good air circulation between the cushioned object and the cushion, resulting in moisture building up between the cushioned object and the bladder (e.g., perspiration from a human body). And eighth, many (but not all) prior art fluid cushions tended to be very heavy. However, fluid cushions which use the composite mixture disclosed in U.S. Pat. Nos. 5,421,874, 5,549,743 and 5,626,657, each of which issued in the name of Pearce, tend to be lightweight.
Examples of fluid cushions include the following: United Kingdom Patent No. 1,261,475 which was published on Jan. 26, 1972; U.S. Pat. No. 5,369,828 issued in the name of Graebe on Dec. 6, 1994; U.S. Pat. No. 5,103,518 issued in the name of Gilroy et al. on Apr. 14, 1992; U.S. Pat. No. 4,945,588 issued in the name of Cassidy et al. on Aug. 7, 1990; U.S. Pat. No. 4,737,998 issued in the name of Johnson, Sr. on Apr. 19, 1988; U.S. Pat. No. 4,485,505 issued in the name of Paul on Dec. 4, 1984; U.S. Pat. No. 4,292,701 issued in the name of Woychick on Oct. 6, 1981; U.S. Pat. No. 3,462,778 issued in the name of Whitney on Aug. 26, 1969; U.S. Pat. No. 2,672,183 issued in the name of Forsyth on Mar. 16, 1954; U.S. Pat. No. 2,814,053 issued in the name of Sevcik on Nov. 26, 1957; U.S. Pat. No. 2,491,557 issued in the name of Goolsbee on Dec. 20, 1949; U.S. Pat. No. 5,100,712 issued in the name of Drew et al. on Mar. 31, 1992; U.S. Pat. No. 5,255,404 issued in the name of Dinsmoor, III et al. on Oct. 26, 1994; U.S. Pat. No. 5,204,154 issued in the name of Drew et al. on Apr. 20, 1993; U.S. Pat. No. 5,201,780 issued in the name of Dinsmoor, III et al. on Apr. 13, 1993; U.S. Pat. No. 5,147,685 issued in the name of Hanson on Sep. 15, 1992; U.S. Pat. No. 5,058,291 issued in the name of Hanson on Oct. 22, 1991; U.S. Pat. No. 5,020,176 issued in the name of Dotson on June 4, 1991; U.S. Pat. No. 5,018,790 issued in the name of Jay on May 28, 1991; U.S. Pat. No. 5,093,138 issued in the name of Drew et al. on Mar. 3, 1992; U.S. Pat. No. 4,842,330 issued in the name of Jay on Jun. 27, 1989; U.S. Pat. No. 4,761,843 issued in the name of Jay on Aug. 9, 1988; U.S. Pat. No. 4,728,551 issued in the name of Jay on Mar. 1, 1988; U.S. Pat. No. 4,726,624 issued in the name of Jay on Feb. 23, 1988; U.S. Pat. No. 4,660,238 issued in the name of Jay on Apr. 28, 1987; U.S. Pat. No. 4,588,229 issued in the name of Jay on May 13, 1986; U.S. Pat. No. 4,483,029 issued in the name of Paul on Nov. 20, 1984; U.S. Pat. No. 4,255,202 issued in the name of Swan, Jr. on Mar. 10, 1981; U.S. Pat. No. 4,247,963 issued in the name of Reddi on Feb. 3, 1981; U.S. Pat. No. 4,243,754 issued in the name of Swan, Jr. on Jan. 6, 1981; U.S. Pat. No. 4,229,546 issued in the name of Swan, Jr. on Oct. 21, 1980; U.S. Pat. No. 4,144,658 issued in the name of Swan, Jr. on Mar. 20, 1979; U.S. Pat. No. 4,083,127 issued in the name of Hanson on Apr. 11, 1978; U.S. Pat. No. 4,038,762 issued in the name of Swan, Jr. on Aug. 2, 1977; U.S. Pat. No. 3,968,213 issued in the name of Lynch on Oct. 19, 1976; and U.S. Pat. No. 3,748,669 issued in the name of Warner on Jul. 31, 1973, each of which is hereby incorporated by reference in its entirety for the material disclosed therein.
3. Gel Cushions: Another design which those in the prior art attempted to employ to create an effective cushion included the use of gelatinous materials ("gels"). Gelatinous materials are soft elastic or viscoelastic materials which easily deform but return to their original shape after the deforming force is removed. The prior art gel cushions had one or more of the following problems. First, gel cushions had a high thermal mass and a high coefficient of thermal transfer, making them cold to the touch and causing them to drain heat out of a cushioned object. Second, gel cushions tended to be costly to manufacture. Third, gel cushions had limited compressibility and therefore did not permit the cushioned object to sink deep into the gel. As a result, only a small surface area of the cushioned object is cushioned by a prior art gel cushion, resulting in a greater supporting force being applied on that small surface area than would be applied if a greater surface area of the cushioned object were to contact the gel cushion for support. This is because in order for the cushioned object to sink into prior art gel cushions, the cushions, which tended to be relatively incompressible, must expand in directions generally normal to the direction of the intended sinking, a behavior which cannot be accommodated in most cushioning applications.
Notwithstanding their problems in the prior art, gel cushions have some attractive features. For example, a gel cushion permits a near-hydrostatic pressure distribution across the surface area of the cushioned object if the cushioned object is allowed to sink into the gel and the overall dimensions of the cushion are not restricted so that such sinking in would be prevented. Also, many gel cushions have the aesthetic advantage, through their shape memory, of being capable of returning to their original shape after the cushioned object is removed.
Documents which disclose gel cushions include: U.S. Pat. No. 5,456,072 issued in the name of Stern on Oct. 10, 1995; U.S. Pat. No. 5,362,834 issued in the name of Schapel et al. on Nov. 8, 1994; U.S. Pat. Nos. 5,336,708, 5,334,646, 5,262,468, 4,618,213 and 4,369,284, each of which issued in the name of Chen; U.S. Pat. No. 5,191,752 issued in the name of Murphy on Mar. 9, 1993; and U.S. Pat. No. 4,913,755 issued in the name of Grim on Apr. 3, 1990, each of which is hereby incorporated by reference in its entirety.
4. Thermoplastic Film Honeycomb Cushions: Another type of cushion in the prior art is made from multiple perforated sheets of pliable thermoplastic film which are intermittently welded together and then expanded into a pliable plastic honeycomb. Honeycomb cushions may have problems such as a high cost of manufacture and an inability to equalize supporting pressure in order to avoid pressure peaks on the most protruding parts of the object being cushioned. This is because of the relatively rigid nature of the thermoplastic and thermoplastic elastomer films used in the honeycomb cushion construction. Honeycomb cushions also carry the risk that the cushioned object will bottom out through the cushion. This is because the films are thin and relatively rigid, so collapsed cells within the cushion offer no real cushioning effect.
The advantages of honeycomb cushions include their light weight. Most of the cushion consists of voids within the cells of the honeycomb, the voids being filled with air, resulting in a lightweight cushion. Another advantage is that honeycomb cushions provide good air circulation between the cushioned object and the cushion due to the perforations in the cell walls of the honeycomb and/or in the facing sheets above and below the honeycomb cells.
Examples of honeycomb or multilayer film cushions are as follows: U.S. Pat. No. 5,445,861 issued in the name of Newton et al. on Aug. 29, 1995; U.S. Pat. No. 5,444,881 issued in the name of Landi et al. on Aug. 29, 1995; U.S. Pat. No. 5,289,878 issued in the name of Landi on Mar. 1, 1994; U.S. Pat. No. 5,203,607 issued in the name of Landi on Apr. 20, 1993; U.S. Pat. No. 5,180,619 issued in the name of Landi et al. on Jan. 19, 1993; U.S. Pat. No. 5,015,313 issued in the name of Drew et al. on May 14, 1991; U.S. Pat. No. 5,010,608 issued in the name of Barnett et al. on Apr. 30, 1991; U.S. Pat. No. 4,959,059 issued in the name of Eilender et al. on Sep. 25, 1990; and U.S. Pat. No. 4,485,568 issued in the name of Landi et al. on Dec. 4, 1984, each of which is hereby incorporated by reference in its entirety.
5. Mattressing: In the prior art there has been work in the field of mattressing, which is considered to be related background against which the invention was made. For references with disclosure relevant to mattressing, the reader is directed to United Kingdom Patent No. 1,261,475 which was published on Jan. 26, 1972; U.S. Pat. No. 5,369,828 issued in the name of Graebe on Dec. 6, 1994; U.S. Pat. No. 5,103,518 issued in the name of Gilroy et al. on Apr. 14, 1992; U.S. Pat. No. 4,945,588 issued in the name of Cassidy et al. on Aug. 7, 1990; U.S. Pat. No. 4,737,998 issued in the name of Johnson, Sr. on Apr. 19, 1988; U.S. Pat. No. 4,485,505 issued in the name of Paul on Dec. 4, 1984; U.S. Pat. No. 4,292,701 issued in the name of Woychick on Oct. 6, 1981; U.S. Pat. No. 3,462,778 issued in the name of Whitney on Aug. 26, 1969; U.S. Pat. No. 2,672,183 issued in the name of Forsyth on Mar. 16, 1954; U.S. Pat. No. 2,814,053 issued in the name of Sevcik on Nov. 26, 1957; and U.S. Pat. No. 2,491,557 issued in the name of Goolsbee on Dec. 20, 1949, each of which is hereby incorporated by reference.
The reader will find that the prior art thus had numerous shortcomings which are addressed by the invented cushion, as outlined below.